1. Field of the Invention
The present invention relates to a method for using an extending super-frame to transfer data in a short distance wireless personal area network (WPAN).
2. Description of the Prior Art
A wireless communication system that satisfies the requirements of a quality of service (QoS) and a property of saving energy for different applications are usually needed. The QoS mainly includes the requirements of a bandwidth, a packet loss rate, a delay, etc. Some medium access control protocols, based on a central control, use a reserved bandwidth technology, such as a Time Division Multiple Access (TDMA) and a Code Division Multiple Access (CDMA), to ensure bandwidth allocation and a certain delay. The property of saving the energy mainly includes a power consumption of a wireless transceiver system itself, and a ratio, i.e., a duty cycle of a workload, between an active period and an inactive period. A high-energy efficient device is usually in a dormant state when not transmitting data and has a small duty cycle. Since the small duty cycle of the workload causes a large delay, it is very hard for the wireless communication system to satisfy the requirements of the QoS and the property of saving the energy at the same time.
As illustrated in FIG. 1, a wireless personal area network (WPAN), which complies with an IEEE802.15.4-2006 standard, satisfies the requirements of the QoS and the property of saving the energy for various applications using a super-frame structure based on the central control. The service guarantee time slot (GTS), which is based on the TDMA technology, can satisfy the bandwidth and the delay requirements of the system in an active period, and can change a ratio between the active period and an inactive period by adjusting a super-frame order and a beacon order, thereby satisfying various properties of saving the energy. However, each general device in the WPAN uses the same super-frame structure as a coordinator, i.e., the same active period and the same inactive period. As such, the WPAN cannot satisfy the requirements of the property of saving the energy and the QoS, i.e., the delay and the bandwidth, at the same time.